1. Field of Invention
The present invention relates to wireless communications. More particularly, the invention is related to a system for improving the transmission of information via short-range communication through an improved multiple antenna arrangement for expanding the otherwise limited operational coverage area of a short-range communication source.
2. Description of Prior Art
A wireless communication device (WCD) may communicate over a multitude of networks. Cellular networks facilitate WCD communications over large geographic areas. For example, the Global System for Mobile Telecommunications (GSM) is a widely employed cellular network that communicates in the 900 MHZ-1.8 GHZ band in Europe and at 1.9 GHZ in the United States. This system provides a multitude of features including audio (voice), video and textual data communication. For example, the transmission of textual data may be achieved via the Short Messaging Service (SMS). SMS allows a WCD to transmit and receive text messages of up to 160 characters. It also provides data transfer to packet networks, ISDN and POTS users at 9.6 Kbps. While cellular networks like GSM provide a global means for transmitting and receiving data, due to cost, traffic and legislative concerns, a cellular network may not be appropriate for all data applications.
Bluetooth™ is a short-range wireless network technology quickly gaining acceptance in the marketplace. A Bluetooth™ enabled WCD may transmit and receive data at a rate of 720 Kbps within a range of 10 meters, and may transmit up to 100 meters with additional power boosting. A user does not manually instigate a Bluetooth™ wireless network. A plurality of devices within operating range of each other will automatically form a network group called a “piconet”. Any device may promote itself to the master of the piconet, allowing it to control data exchanges with up to seven “active” slaves and 255 “parked” slaves. Active slaves exchange data based on the clock timing of the master. Parked slaves monitor a beacon signal in order to stay synchronized with the master, and wait for an active slot to become available. These devices continually switch between various active communication and power saving modes in order to transmit data to other members of the piconet.
More recently, manufacturers have began to incorporate various devices for providing enhanced functionality in a WCD (e.g., hardware components and software for performing close-proximity wireless information exchanges). Sensors and/or scanners may be used to read visual or electronic information into a device. A transaction may involve a user holding their WCD in proximity to a target, aiming their WCD at an object (e.g., to take a picture), sweeping the device over a tag or document, etc. Machine-readable technologies such as radio frequency identification (RFID), Infra-red (IR) communication, optical character recognition (OCR) and various other types of visual, electronic and magnetic scanning are used to quickly input desired information into the WCD without the need for manual entry by a user.
Short-range communication strategies are ideal for business entities seeking to reach information consumers in a designated geographic area. Short-range communications are mostly unregulated, and are generally a cost-effective solution for making data available to a potential recipient. For example, a business may set up a local access point to service customers that come within proximity of the access point. The Nokia Local Marketing Solution and iJack™ by TeliaSonera Finland Oyj are two examples of these local information delivery systems. These services use hardware access points communicating via Bluetooth™ to create piconets including accessible devices that come within transmission range. The service point becomes the master device, and may download price, coupon, show time, date, reservation information, etc. to a potential client. In another application, these systems may also be used to impart work-relevant data to employees or educational information to students, etc. While these systems may work automatically to impart desired information to a consumer, they are limited by the time required to both establish a network and download content. Often, an information consumer will not remain within range of an access point long enough to receive all of the information to be delivered by the device (e.g., a person strolling by a storefront), defeating the primary purpose of establishing the service point.
An alternative to downloading all of the desired information via short-range communication at the time of first contact would be to simply download a pointer, bookmark, indicator, link, etc. to the desired information. The downloaded pointer might include a website address (URL), email address, phone number, etc. that would in turn allow the device user to obtain the body of the desired information at a later time, for instance, from a dedicated short-range service point, via long-range data communication, via a wired internet connection, via a telephone, etc.
In at least one example of short-range machine-readable communication, RFID may be employed to convey several kilobytes worth of data to a scanning device in a relatively short amount of time. In addition, a passive RFID transponder or “tag” does not require its own power source. The tag receives power from the scanning device. Therefore, the passive tag may be imbedded in any manner of structure such as a poster, display, standee, doorway, wall, etc. A user passing near the tag may manually or automatically scan the tag and receive a response including desired information in a relatively short amount of time.
In at least the case of RFID communication, the already short effective communication range of the scanner/tag transponder (as short as 2-5 cm for a low power mobile device containing a scanner) may be further limited by the configuration or composition of the structure in which it is embedded. Certain materials may interfere with radio frequency waves, requiring a user to come closer to the tag in order to make contact. The resulting situation may create a “traffic jam” of users trying to get into the same area in order to receive the desired information. Therefore, what is needed is a way to extend the effective range of the machine-readable data so that a plurality of data users over an extended effective range may receive information from the same tag.
Various methods are known in the art for increasing the range of a machine-readable tag via extended antenna configurations. However, these configurations often involve a complex antenna structure hardwired to the tag intended to handle only one scanning device at a time. What is needed is a method including some intelligence for determining the source of a plurality of scanning signals and for adjusting the antenna system to account for these multiple scanners. The system must be able to select between active sources in order to return desired information back to a scanner while managing the loading of the antenna system.